What’s most surprising about Paul McCartney’s new LP is not that it’s full of pre-rock pop standards, but that it took him so long to get around to this kind of project. He was the son of a jazz band leader who turned the future Beatle on to songs like 1933’s "It’s Only a Paper Moon," among the tunes covered here. McCartney’s writing always had old-school flavor: "WhenI’m Sixty-Four" and "Martha My Dear" evoked vaudeville; "Yesterday" echoed Nat "King" Cole’s style. Like Rock 'n' Roll, John Lennon’s 1975 album of primal rock gems, Kisses on the Bottom is the sound of a musician joyfully tapping his roots; and like his former song writing partner, McCartney is better transforming influences than mirroring them. But it’s fun, and touching, to hear him crooning his way through the great American songbook.

McCartney clearly loves the sentimentality these tunes thrive on. "More I Cannot Wish You," from the 1950 musical Guys and Dolls, is wrapped in a lush orchestral arrangement by Sinatra vet Johnny Mandel, and McCartney sinks into it with the avuncular warmth that flickered through "Let It Be." On Fats Waller’s "My Very Good Friend the Milkman," McCartney invokes a lost world where lovers courted via postal service, singing in a sugared half-whisper. As the title suggests – a cheeky pun from "I’m Gonna Sit Right Down and Write Myself a Letter," another Waller cover – McCartney also revels in the lyrical wit."We three/We’re not a crowd/We’re not even company," hesings on "We Three (My Echo,My Shadow, and Me)," a hit for the proto-doo-wop vocal group the Ink Spots. Context also adds humor: See the 1926 standard "Bye Bye Blackbird," which always vied with McCartney’s "Blackbird" for the species theme song.

Remarkably, aside from some acoustic guitar, Macca doesn’t touch an instrument. The ensemble is led by Diana Krall, a jazz-pop pianist who now has a track record of wooing British rockers – like Elvis Costello, her husband. With some A-list jazzbos (including drummer Karriem Riggins), the group complements McCartney’s playfulness while trying to steer clear of corn. Krall’s cozy swing animates "It’s Only a Paper Moon," and even "The Inch Worm" is rescued from the kindergarten curriculum. Cameos imprint the two McCartney originals, which hold their own. "My Valentine" recalls Cole’s take on "My Funny Valentine" and features supple acoustic guitar by Eric Clapton. The slow dance "Only Our Hearts" is brightened by a Stevie Wonder harmonica solo.

There’s an irony here: The Beatles played a big role in permanently confining this style of pop to the margins. And if McCartney doesn’t bring much beyond his beloved timbre to these melodies, there’s a lovely honesty to the set, which reads in part as a love letter to Nancy Shevell, the new Mrs. McCartney. One imagines, had things played out differently, her hook loving husband might have wound up doing just this: happily playing standards, with miles of charm, for whomever turned up at the pub.